The present invention relates to a novel use of calcitonin in osteoarthritis, and to methods of treating and/or preventing osteoarthritis in mammals, particularly humans.
Calcitonins, e.g. salmon, (Asu 1-7)-eel or human calcitonin, of the invention are compounds which are long-chain polypeptide hormones secreted by the parafollicular cells of the thyroid gland in mammals and by the ultimobranchial gland of birds and fish. Calcitonin is mainly known as a potent inhibitor of osteoclastic bone resorption, which implicates bone attachment of osteoclasts and enzymatic degradation. Furthermore, it was found that there are effects of Intranasal Salmon Calcitonin in Juvenile Idiopathic Arthritis in humans (Siamopoulou A. et al, 2001, Calcif Tissue Int 69: 25-30) and in the prevention of bone erosion and bone loss in rheumatoid arthritis in humans (Sileghem A., 1992, Annals of Rheumatic Diseases 51: 761-764). The degradative process associates synthesis of various proteases and metalloproteinases, activation of inactive proenymes and inhibition of active enzymes (Leloup G, 1994, J Bone Miner Res, 9, 891-902). Calcitonin is known to induce osteoclast retraction (Zheng M H, et al., 1992, Exper Mole Pathol, 57: 105-115) and to interfere at least with some steps of the enzymatic process of bone resorption (Einhorn T A et al., 1991, Clin Orthop 262: 286-297). There are some reported studies on the effects of calcitonin on articular cartilage. In vitro, calcitonin was found to stimulate proteoglycan and collagen synthesis in animal epiphyseal cartilage (Baxter et al., 1984, Endocrinology 114: 1196-1202) as well as in rabbit and human cartilage (Franchimont P, 1989, J Clin End Metab 69: 259-266). The study of calcitonin in the treatment of experimental osteoarthritis gave conflicting results. E.g. calcitonin was found to prevent cartilage destruction in rabbits treated with steroids, partial menisectomy or joint immobilization (Badurski J E et al., 1991, Lab Invest 49: 27-34), but no effect on cartilage was observed in another menisectomy model (Colombo et al., 1983, Arthritis Rheum 26: 1132-1139). Moreover, the relative importance of cartilage and bone changes in the Initiation and progression of osteoarthritis is still being debated. No study in humans has yet shown to our knowledge the efficacy of calcitonin in osteoarthritis.